The present invention relates to a power factor correction device and its control method and, for example, can be suitably applied to a switching power supply unit of an AC/DC converter or the like.
Conventionally, as a power supply unit, broadly used is a type with a power factor collection circuit (hereinafter referred to as the “PFC (Power Factor Correction) circuit”) configured from a choke coil, a switching element and a capacitor disposed at the subsequent stage of a full wave rectification circuit for outputting an absolute value of a commercial AC (refer to Japanese Patent Application Publication No. 2007-288892).
This type of PFC circuit generates a triangle wavelike coil current in the choke coil by subjecting the switching element to ON/OFF operation at a high frequency, performs rectification smoothing to the coil current with a capacitor, corrects the input current to a sine wave of the same phase as the input voltage, and thereby outputs the same.